Title: Modeling RBF efficacy for migrating chemical shock loads

Title: Mass transport modelling to assess contamination of a water supply well

in Sabarmati river bed aquifer, Ahmedabad City, India

Author(s): Rao VVSG , Gupta SK

Source: ENVIRONMENTAL GEOLOGY 39 (8): 893-900 JUN 2000

Document Type: Article

Language: English

Cited References: 9 Times Cited: 0

Abstract: Drinking water supply wells were constructed in the Sabarmati river bed aquifer of Ahmedabad city using radial pipes and are known as French Collector wells.

Contamination of groundwater from one of the French wells near Sabarmati railway bridge was noticed in 1992. The suspected pollution sources are Duff-nala of Shahibaug and two other sources from slum dwellings on either side of Sabarmati river. A combined groundwater flow, pathlines and a mass transport model was constructed covering an area of 9 km(2) to analyse the capture zone of the French well under two different scenarios. Aquifer parameters of the river bed aquifer were available. Dry river bed condition was simulated under scenario I and controlled flow in the river bed was simulated under scenario II. The groundwater velocity and migration of contaminant particles from sources was analysed in the pathline model. Total dissolved solids (TDS) concentration contours originating from sources in the mass transport model (MT3D) were computed by solving an advection-dispersion equation. The computed pathlines and

TDS concentration contours indicate likely migration of contaminant plume from pollutant sources to the French well during 365 days under two scenarios. The model results confirm the tracer injection studies carried out to know the likely migration of contaminants towards the French well. The modelling study emphasised the necessity of controlled release of surface water in Sabarmati river bed from Dharoi reservoir throughout the year.

Author Keywords: flow model; mass transport; pathlines; groundwater velocity;

Sabarmati river; French collector well; dry river bed; tracer

Addresses: Rao VVSG (reprint author), Natl Geophys Res Inst, Hyderabad, Andhra

Pradesh 500007 India

Natl Geophys Res Inst, Hyderabad, Andhra Pradesh 500007 India

Phys Res Lab, Ahmedabad, Gujarat 380009 India

Publisher: SPRINGER VERLAG, 175 FIFTH AVE, NEW YORK, NY 10010 USA

Title: A mixing model analysis of stream solute dynamics and the contribution of

a hyporheic zone to ecosystem function

Author(s): Battin TJ , Kaplan LA , Newbold JD , Hendricks SP

Source: FRESHWATER BIOLOGY 48 (6): 995-1014 JUN 2003




Abstract: 1. We monitored streamwater and streambed sediment porewaters from White

Clay Creek (WCC), SE Pennsylvania, for dissolved organic carbon (DOC), dissolved oxygen (DO) and conductivity to investigate organic matter processing within the hyporheic zone. Dissolved organic carbon and DO concentrations were higher in the streamwater than in the porewaters and, in many cases, concentrations continued to diminish with increasing depth into the streambed.

2. Hydrological exchange data demonstrated that the permeability of the stream bed declines with depth and constrains downwelling, effectively isolating porewaters >30 cm from streamwater.

3. End-member mixing analysis (EMMA) based on conductivity documented a DOC source and DO sink in the hyporheic zone. We calculated hyporheic streambed DOC fluxes and

respiration from the EMMA results and estimates of water flux. Based upon our calculations of biodegradable DOC entering the hyporheic zone, we estimate that DOC supports 39% of the hyporheic zone respiration, with the remaining 61% presumably being supported by entrained particulate organic carbon. Hyporheic respiration averaged

0.38 g C m(-2) d(-1) , accounted for 41% of whole ecosystem respiration, and increased baseflow ecosystem efficiency from 46 to 59%.

4. Advective transport of labile organic molecules into the streambed concentrates microbial activity in near-surface regions of the hyporheic zone. Steep gradients in biogeochemical activity could explain how a shallow and hydrologically constrained hyporheic zone can dramatically influence organic matter processing at the ecosystem scale.

Author Keywords: dissolved organic carbon; ecosystem function; end-member mixing analysis; hydrodynamic exchange; hyporheic zone

KeyWords Plus: DISSOLVED ORGANIC-CARBON; VERTICAL HYDROLOGIC EXCHANGE;

SURFACE-WATER; COMMUNITY RESPIRATION; BACTERIAL BIOMASS; HEADWATER

STREAMS; TEMPERATE STREAM; MOUNTAIN STREAM; DESERT STREAM; METABOLISM

Addresses: Kaplan LA (reprint author), Stroud Water Res Ctr, 970 Spencer Rd, Avondale,

PA 19311 USA

Stroud Water Res Ctr, Avondale, PA 19311 USA

Hancock Biol Stn, Murray, KY USA

Publisher: BLACKWELL PUBLISHING LTD, 9600 GARSINGTON RD, OXFORD OX4 2DG,

OXON, ENGLAND

Subject Category: MARINE & FRESHWATER BIOLOGY

IDS Number: 679YA

Title: Macroscopic models for predicting changes in saturated porous media

properties caused by microbial growth

Author(s): Clement TP , Hooker BS , Skeen RS

Source: GROUND WATER 34 (5): 934-942 SEP-OCT 1996




Abstract: Analytical equations are developed to model changes in porosity, specific surface area, and permeability caused by biomass accumulation in porous media. The proposed equations do not assume any specific pattern for microbial growth but instead are based on macroscopic estimates of average biomass concentrations. For porous media with a pore-size distribution index value (lambda) equal to 3, the macroscopic model predictions of porosity, specific surface area, and permeability changes are in exact agreement with biofilm-model predictions, At other values of lambda between 2 and 5, simulated porosity profiles are identical and relative specific surface area and permeability profiles show minor deviations, In comparison to biofilm-based models, the macroscopic models are relatively simple to implement and are computationally more efficient. Simulations of biologically reactive flow in a one-dimensional column shaw that the macroscopic and biofilm approach based transport codes predict almost identical porosity and permeability profiles, The macroscopic models are simple and useful tools for estimating changes in various porous media properties during bioremediation of contaminated aquifers.

Title: Modeling of a microbial growth experiment with bioclogging in a two-

dimensional saturated porous media flow field

Author(s): Thullner M , Schroth MH , Zeyer J , Kinzelbach W

Source: JOURNAL OF CONTAMINANT HYDROLOGY 70 (1-2): 37-62 MAY 2004




Abstract: A model was developed simulating reactive transport in groundwater including bioclogging. Results from a bioclogging experiment in a flow cell with a two-dimensional flow field were used as a data base to verify the simulation results of the model.

Simulations were performed using three different hydraulic conductivity vs. porosity relations published in literature; two relations derived from pore network simulations assuming the biomass to grow in discrete colonies and as a biofilm, respectively, and a third relation, which did not include pore connectivity in more than one dimension. Best agreement with the experimental data was achieved using a hydraulic conductivity vs. porosity relation derived from pore network simulation assuming the biomass to grow in colonies. The relation derived from pore network simulations assuming biomass to grow as a biofilm was unable to reproduce the experimental data when realistic parameter values were employed. With the third relation the clogging ability of the biomass was strongly underestimated. These findings indicate that the porous medium needs to be treated as a multi-dimensional medium already on the pore scale, and that biomass growth different than in a biofilm must be considered to get an appropriate description of bioclogging. (C) 2003 Elsevier B.V All rights reserved.

Author Keywords: biological clogging; hydraulic conductivity; biomass; simulation

Title: Considerations for modeling bacterial-induced changes in hydraulic

properties of variably saturated porous media

Author(s): Rockhold ML , Yarwood RR , Niemet MR , Bottomley PJ , Selker JS

Source: ADVANCES IN WATER RESOURCES 25 (5): 477-495 MAY 2002

Document Type: Review



Abstract: Bacterial-induced changes in the hydraulic properties of porous media are important in a variety of disciplines. Most of the previous research on this topic has focused on liquid-saturated porous media systems that are representative of aquifer sediments. Unsaturated or variably saturated systems such as soils require additional considerations that have not been fully addressed in the literature. This paper reviews some of the earlier studies on bacterial-induced changes in the hydraulic properties of saturated porous media, and discusses characteristics of unsaturated or variably saturated porous media that may be important to consider when modeling such phenomena in these systems. New data are presented from experiments conducted in sand-packed columns with initially steady unsaturated flow conditions that show significant biomass-induced changes in pressure heads and water contents and permeability reduction during growth of a Pseudomonas fluorescens bacterium. (C) 2002

Elsevier Science Ltd. All rights reserved.

Title: Experimental observations and numerical modeling of coupled microbial

and transport processes in variably saturated sand

Author(s): Rockhold ML , Yarwood RR , Niemet MR , Bottomley PJ , Selker JS

Source: VADOSE ZONE JOURNAL 4 (2): 407-417 APR 2005




Abstract: An experimental and numerical investigation was conducted to study interactions between microbial dynamics and transport processes in variably saturated porous media. Experiments were conducted with constant, surface-applied water fluxes in duplicate, variably saturated, sand-filled columns that were uniformly inoculated with the bacterium Pseudomonas fluorescens HK44. The permeability of the sand in the columns was reduced by a factor of 45 during 1 wk of growth on glucose. Pressure heads increased ( became less negative) at all measured depths, but significant increases in the apparent volumetric water contents were observed in only the upper 5 cm of the columns, corresponding to the areas with the highest concentrations of attached bacteria. A numerical model was used to simulate the experiments. The model accounted for the processes of water flow, solute and bacterial transport, cell growth and accumulation, and

O-2 consumption, and gas diffusion and exchange. Observed changes in water content and pressure head were reproduced approximately using fluid-media scaling to account for an apparent surface-tension lowering effect. Reasonable correspondence was obtained between observed and simulated effluent data and final attached biomass concentration distributions using first-order reversible cell attachment and detachment kinetics. The attachment rate coefficients were based on particle-filtration theory and time-dependent detachment rate coefficients. The results of this study illustrate the potential importance of using fully coupled multifluid flow and multicomponent reactive transport equations to model coupled biogeochemical and transport processes in soils.

Title: Impact of microbial activity on the hydraulic properties of fractured chalk

Author(s): Arnon S , Adar E , Ronen Z , Yakirevich A , Nativ R

Source: JOURNAL OF CONTAMINANT HYDROLOGY 76 (3-4): 315-336 FEB 2005




Abstract: The impact of microbial activity on fractured chalk transmissivity was investigated on a laboratory scale. Long-term experiments were conducted on six fractured chalk cores (20 cm diameter, 23-44 cm long) containing a single natural fracture embedded in a porous matrix. Biodegradation experiments were conducted under various conditions, including several substrate and oxygen concentrations and flow rates. 2,4,6-Tribromophenol (TBP) was used as a model contaminant (substrate). TBP biodegradation efficiency depended mainly on the amount of oxygen. However, under constant oxygen concentration at the core inlet, elevating the flow rates increased the removal rate of TBP. Transmissivity reduction was clearly related to TBP removal rate, following an initial slow decline and a further sharp decrease with time. The fracture's transmissivity was reduced by as much as 97% relative to the initial value, with no leveling off of the clogging process. For the most extreme cases, reductions of 262 and

157 mum in the equivalent hydraulic apertures were recorded for fractures with initial apertures of 495 and 207 mum, respectively. The reductions in fracture transmissivity occurred primarily because of clogging by bacterial cells and extracellular polymeric substances (EPS) produced by the bacteria. Most of the biodegradation activity was concentrated near the fracture inlet, where the most suitable biodegradation conditions

(nutrients and oxygen) prevailed, suggesting that the clogging bad occurred in that vicinity. The clogging must have changed the structure of the fracture void, thereby reducing the active volume participating in flow and transport processes. This phenomenon caused accelerated transport of non-reactive tracers and doubled the fracture's dispersivitv under constant flow rates. (C) 2004 Elsevier B.V. All rights reserved.

Title: Laboratory tests for simulating attenuation processes of aromatic amines

in riverbank filtration

Author(s): Worch E , Grischek T , Bornick H , Eppinger P

Source: JOURNAL OF HYDROLOGY 266 (3-4): 259-268 SEP 15 2002


Language: English Cited References: 18 Times Cited: 4

Abstract: Based on a two-step laboratory test including biodegradation and adsorption, it is possible to derive a prognosis of the behaviour of organic compounds during

riverbank filtration and to prioritise the substances with regard to drinking water quality. It is shown for aromatic amines, used as an example of organics found in River

Elbe water, Germany, how the simulation methods provide basic information about rate constants of biological degradation and adsorption equilibrium constants under conditions that are as realistic as possible. Biodegradation of nitroanilines and higher chlorinated anilines is relatively slow and adsorption onto the sandy aquifer material is weak.

Accordingly, occurrence of these compounds in the production wells of the waterworks cannot be excluded. (C) 2002 Elsevier Science B.V. All rights reserved.

Author Keywords: bank filtration; aromatic amines; biodegradation; adsorption

KeyWords Plus: SORPTION; COEFFICIENTS; SEDIMENTS; WATER

Title: Contaminant transport in riverbank filtration in the presence of dissolved

organic matter and bacteria: a kinetic approach

Author(s): Kim SB , Corapcioglu MY

Source: JOURNAL OF HYDROLOGY 266 (3-4): 269-283 SEP 15 2002




Abstract: In riverbank filtration, the removal of organic contaminants is an important task for the production of good quality drinking water. The transport of an organic contaminant in riverbank filtration can be retarded by sorption on to the solid matrix and facilitated by the presence of mobile colloids. In the presence of dissolved organic matter (DOM) and bacteria, the subsurface environment can be modeled as a four-phase porous medium: two mobile colloidal phases, an aqueous phase, and a solid matrix. In this study, a kinetic model is developed to simulate the contaminant transport in

riverbank filtration in the presence of DOM and bacteria. The bacterial deposition and the contaminant sorption on bacteria and DOM are expressed with kinetic expressions.

The model equations are solved numerically with a fully implicit finite difference method.

Simulation results show that the contaminant mobility increases greatly in riverbank

filtration due to the presence of DOM. The mobility can be enhanced further when the bacteria and DOM are present together in the aquifer. In this system, the total aqueous phase contaminant concentration, C-ct(+) includes the contaminant dissolved in the aqueous phase, C-c(+) the contaminant sorbed to DOM, sigma(cd)(+), and the contaminant sorbed to mobile bacteria, C(b)(+)sigma(cbm)(+),(i.e. C-ct(+) = C-c(+) + sigma(cd)(+) + C-b(+) sigma(cbm)(+)) Sensitivity analysis illustrates that the distribution of the total aqueous phase contaminants among the dissolved phase, DOM and bacteria is changed significantly with various Damkohler numbers related to the contaminant sorption on mobile colloids. (C) 2002 Elsevier Science B.V. All rights reserved.

Author Keywords: riverbank filtration; contaminant transport; colloids; dissolved organic matter; bacteria

KeyWords Plus: GROUNDWATER-INFILTRATION; LABORATORY COLUMN; ALLUVIAL

AQUIFER; MOBILE BACTERIA; POROUS-MEDIA; WATER; FIELD; HYDROCARBONS;

SOLUBILITY; COLLOIDS

Addresses: Kim SB (reprint author), Texas A&M Univ, Dept Civil Engn, College Stn, TX

77843 USA

Texas A&M Univ, Dept Civil Engn, College Stn, TX 77843 USA

Title: Modeling floodplain filtration for the improvement of river water quality

Author(s): Chung JB , Kim SH , Jeong BR , Lee YD , Prasher S

Source: TRANSPORT IN POROUS MEDIA 60 (3): 319-337 SEP 2005




Abstract: A mathematical model was developed to describe a treatment method of floodplain filtration for the improvement of river water quality. The process consists of spraying poor quality river water onto the river floodplains and thus allowing soil filtration to treat water before it gets back again into the main river stream. This technique can be readily employed in Korea because it exploits the characteristics of the climate and rivers in the country, as described in an experimental study of Chung et al. ( 2004). The model was analyzed by numerical methods and validated by comparing the simulated values with experimental data. A scenario analysis of the model was also performed in order to have a better understanding of the. oodplain filtration process. Our results show that the model was able to predict the reduction in organic matter and NO3- in river water through the. oodplain filtration. Furthermore, it was found that only a few decimeters of top soil profile were enough to degrade most of the organic matter under wider operational conditions than those reported in the literature. Also, it was found that significant infiltration of atmospheric oxygen took place near the soil surface. The N2O emission and the NO3- leaching increased with the increase in the influent NO3- concentration. However, the N2O emission due to. oodplain filtration was not expected to exceed 0.1 mL/m(2)-day.

Author Keywords: floodplain filtration; organic matter removal; denitrification; mathematical modeling; competitive Michaelis-Menten model

KeyWords Plus: POROUS-MEDIA; DENITRIFICATION PROCESSES; KINETIC

FORMULATION; OXYGEN-CONSUMPTION; MICROBIAL-GROWTH; ORGANIC-MATTER;

SOIL; NITROGEN; TRANSPORT; SUBSURFACE

Addresses: Kim SH (reprint author), Yeungnam Univ, Dept Environm Engn, Gyongsan,

712749 South Korea

Yeungnam Univ, Dept Environm Engn, Gyongsan, 712749 South Korea

Daegu Univ, Dept Agr Chem, Gyongsan, 712714 South Korea

Daegu Univ, Dept Agron, Gyongsan, 712714 South Korea

McGill Univ, Dept Agr & Biosyst Engn, Ste Anne De Bellevue, PQ H9X 3V9 Canada

E-mail Addresses: kimsh@yumail.ac.kr

Title: River bank filtration: Modelling of the changes in water chemistry with

emphasis on nitrogen species

Author(s): Doussan C , Poitevin G , Ledoux E , Detay M

Source: JOURNAL OF CONTAMINANT HYDROLOGY 25 (1-2): 129-156 FEB 1997




Abstract: Bank-filtrated water is an important component of the drinking water production in many countries. The changes in the water chemistry during the transfer

from the river to the aquifer have important implications for the quality of the produced water. In this paper, we first describe certain features of the evolution of the water chemistry during bank-filtration in the case of an experimental site, part of a large well field (Seine river, France). Here, bank-filtration leads to highly reducing conditions in the aquifer. A conceptual and numerical macroscopic model of this evolution, focusing on nitrogen compounds, is then presented. The model is designed to simulate organic matter mineralization and redox reactions catalyzed by bacteria in the river bed sediments where water infiltrates. Growth and decay of bacteria are explicitly accounted for and a numerical solution is found with an operator splitting technique. The model is able to reproduce column experiments by von Gunten and Zobrist (1993) designed to simulate infiltration of organically polluted river water into an aquifer. A model application to the characteristics of the experimental site is also presented. Results of a sensitivity analysis highlight the importance of: (1) the flow rate of water infiltrating river bed sediments; and (2) the organic carbon content of these sediments, for the evolution of the water quality during transfer from the river to the aquifer. (C) 1997 Elsevier Science B.V.

Author Keywords: groundwater; denitrification; ammonification; model; bacteria; sediments

KeyWords Plus: POROUS-MEDIA; TRANSPORT MODEL; SANDY AQUIFER; GROUND-

WATER; BIODEGRADATION; INFILTRATION; OXYGEN; DENITRIFICATION; SIMULATIONS;

SUBSURFACE

Addresses: Doussan C (reprint author), INRA, UNITE SCI SOL, DOMAINE ST PAUL, SITE

AGROPARC, AVIGNON, F-84914 FRANCE

ECOLE MINES, CTR INFORMAT GEOL, FONTAINEBLEAU, F-77305 FRANCE

LAB CENT LYONNAISE EAUX, CHOLET, F-49300 FRANCE

Publisher: ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS

Subject Category: GEOSCIENCES, MULTIDISCIPLINARY; ENVIRONMENTAL SCIENCES;

WATER RESOURCES

Title: Parameter estimation of the transient storage model for stream-

subsurface exchange

Author(s): Marion A , Zaramella M , Packman AI

Source: JOURNAL OF ENVIRONMENTAL ENGINEERING-ASCE 129 (5): 456-463 MAY

2003




Abstract: The transient storage model (TSM) is the most commonly used model for stream-subsurface exchange of solutes. The TSM provides a convenient, simplified representation of hyporheic exchange, but its lack of a true physical basis causes its parameters to be difficult to predict. However, the simple formulation makes the model a useful practical tool for many applications. This work compares the TSM with a physically based pumping model. This comparison is advantageous for two reasons: Advective pumping is known to be an important hyporheic exchange process in many streams, and the pumping model can be used to derive dimensionless transient storage parameters that are properly scaled with important physical stream parameters. Transient storage model parameters are shown to be dependent on both the timescale of observation and the shape of the breakthrough curve, i.e., on the temporal evolution of the solute concentration in the surface water. This indicates that the transient storage model can, in practice, lead to incorrect predictions when model parameters are obtained without consideration of the stream flow dynamics, the properties of the stream bed, or the process timescale. This work emphasizes the limitations of simplified models for hyporheic transport, and indicates that such models need to be carefully applied.

Author Keywords: models; subsurface environment; solutes; hydraulic transients; streams

KeyWords Plus: BENTHIC OXYGEN-UPTAKE; SOLUTE TRANSPORT; BED FORMS;

LABORATORY EXPERIMENTS; CONVECTIVE-TRANSPORT; NONSORBING SOLUTES;

MOUNTAIN STREAM; WATER EXCHANGE; HYPORHEIC ZONE; CHANNEL

Addresses: Marion A (reprint author), Univ Padua, Dept Hydraul Maritime Environm &

Geotech Engn, Via Loredon 20, Padua, I-35100 Italy

Univ Padua, Dept Hydraul Maritime Environm & Geotech Engn, Padua, I-35100 Italy

Northwestern Univ, Dept Civil & Environm Engn, Evanston, IL 60208 USA

Publisher: ASCE-AMER SOC CIVIL ENGINEERS, 1801 ALEXANDER BELL DR, RESTON, VA

20191-4400 USA

Subject Category: ENGINEERING, CIVIL; ENGINEERING, ENVIRONMENTAL;

ENVIRONMENTAL SCIENCES

IDS Number: 668MJ

ISSN: 0733-9372

Title: Sensitivity analysis of conservative and reactive stream transient storage

models applied to field data from multiple-reach experiments

Author(s): Gooseff MN , Bencala KE , Scott DT , Runkel RL , McKnight DM

Source: ADVANCES IN WATER RESOURCES 28 (5): 479-492 MAY 2005




Abstract: The transient storage model (TSM) has been widely used in studies of stream solute transport and fate, with an increasing emphasis on reactive solute transport. In this study we perform sensitivity analyses of a conservative TSM and two different reactive solute transport models (RSTM), one that includes first-order decay in the stream and the storage zone, and a second that considers sorption of a reactive solute on streambed sediments. Two previously analyzed data sets are examined with a focus on the reliability of these RSTMs in characterizing stream and storage zone solute reactions.

Sensitivities of simulations to parameters within and among reaches, parameter coefficients of variation, and correlation coefficients are computed and analyzed. Our results indicate that (1) simulated values have the greatest sensitivity to parameters within the same reach, (2) simulated values are also sensitive to parameters in reaches immediately upstream and downstream (inter-reach sensitivity), (3) simulated values have decreasing sensitivity to parameters in reaches farther downstream, and (4) instream reactive solute data provide adequate data to resolve effective storage zone reaction parameters, given the model formulations. Simulations of reactive solutes are shown to be equally sensitive to transport parameters and effective reaction parameters of the model, evidence of the control of physical transport on reactive solute dynamics.

Similar to conservative transport analysis, reactive solute simulations appear to be most sensitive to data collected during the rising and falling limb of the concentration breakthrough curve. (c) 2005 Elsevier Ltd. All rights reserved.

Author Keywords: solute transport; tracer; reactive transport; sensitivity analysis;

OTIS; UCODE

KeyWords Plus: GLACIAL MELTWATER STREAM; SOLUTE TRANSPORT; HYPORHEIC

ZONE; RIFFLE STREAM; MASS-TRANSFER; EXCHANGE; SIMULATION; SORPTION;

TRACER; IRON

Addresses: Gooseff MN (reprint author), Colorado Sch Mines, Dept Geol & Geol Engn,

Golden, CO 80401 USA

Colorado Sch Mines, Dept Geol & Geol Engn, Golden, CO 80401 USA

US Geol Survey, Div Water Resources, Menlo Pk, CA 94025 USA

US Geol Survey, Div Water Resources, Reston, VA 22092 USA

US Geol Survey, Denver Fed Ctr, Denver, CO 80225 USA

Univ Colorado, Inst Arctic & Alpine Res, Boulder, CO 80309 USA

E-mail Addresses: mgooseff@mines.edu

Title: Application of the transient storage model to analyze advective hyporheic

exchange with deep and shallow sediment beds

Author(s): Zaramella M , Packman AI , Marion A

Source: WATER RESOURCES RESEARCH 39 (7): Art. No. 1198 JUL 31 2003




Abstract: Hydrodynamic exchange between a stream and its bed plays an important role in solute transport in rivers. Stream-subsurface exchange is known to occur due to several different mechanisms and different approaches have been used to model the resulting solute transport, but there has been little investigation of the ability of the various models to represent specific exchange processes. This work evaluates the ability of the semiempirical transient storage model (TSM) to represent advective hyporheic exchange driven by bed form-induced pore water flows. The TSM is based on the idealized hypothesis that the flux of contaminants is proportional to the difference in concentration between the bed and the stream. To evaluate the ability of this simplified mass transfer relationship to reproduce advective hyporheic exchange, we apply the TSM to data sets for the exchange of conservative solutes with sand beds in laboratory flumes where bed form-induced pumping is the dominant exchange mechanism. The results show that the simplified expressions used in the TSM can represent some but not all aspects of the pumping process. The TSM can represent advective exchange with shallow beds that have a defined exchange layer restricted by the presence of an impermeable boundary. In this case, transient storage parameters can be directly related to the streamflow conditions and the channel geometry. However, the TSM does not do a good job of representing exchange with a relatively deep sediment bed, where flow along different advective paths in the bed yields a wide distribution of exchange timescales.

Author Keywords: hyporheic exchange; transient storage; solute transport; streams; stream-subsurface interactions; modeling

KeyWords Plus: STREAM-SUBSURFACE EXCHANGE; LABORATORY EXPERIMENTS;

CONVECTIVE-TRANSPORT; NONSORBING SOLUTES; WATER EXCHANGE; TRACER;

RIVERS; FORMS; GROUNDWATER

Addresses: Zaramella M (reprint author), Univ Padua, Dept Hydraul Maritime & Geotech

Engn, Via Loredan 20, Padua, I-35100 Italy

Univ Padua, Dept Hydraul Maritime & Geotech Engn, Padua, I-35100 Italy

Northwestern Univ, Dept Civil Engn, Evanston, IL 60208 USA

Publisher: AMER GEOPHYSICAL UNION, 2000 FLORIDA AVE NW, WASHINGTON, DC

20009 USA

Subject Category: ENVIRONMENTAL SCIENCES; LIMNOLOGY; WATER RESOURCES

IDS Number: 710ZG

Title: Predicting chlorine residuals and formation of TTHMs in drinking water

Author(s): Clark RM , Sivaganesan M

Source: JOURNAL OF ENVIRONMENTAL ENGINEERING-ASCE 124 (12): 1203-1210 DEC

1998




Abstract: Chlorination is the most widely practiced form of disinfection in the United

States. It is highly effective against most microbiological contaminants. However, there is concern that the disinfection by-products (DBPs) formed by the use of chlorine might be carcinogenic. One class of DBPs that are formed and the only class of DBPs that currently

are regulated are total trihalomethanes (TTHMs). Therefore, much effort is being expended in developing models that can be used to predict both TTHMs and chlorine residual levels in treated drinking water. This paper presents a model that predicts both

TTHMs and chlorine residuals based on the consumption of chlorine and can be used to assist in evaluating the complex balance between microbial and DBP risks associated with disinfecting drinking water with chlorine. The parameters of the model have been found to be functions of total organic carbon, pH, temperature, and initial chlorine residual level.

Bromide and the subsequent formation of brominated by-products were not considered in this paper.

KeyWords Plus: BROMIDE

Addresses: Clark RM (reprint author), US EPA, Water Supply & Water Resour Div, Nat

Risk Mgmt Res Lab, 26 W Martin L King Dr, Cincinnati, OH 45268 USA

US EPA, Water Supply & Water Resour Div, Nat Risk Mgmt Res Lab, Cincinnati, OH 45268

USA

ALM Joint Venture, Cincinnati, OH 45202 USA

Publisher: ASCE-AMER SOC CIVIL ENGINEERS, 345 E 47TH ST, NEW YORK, NY 10017-

2398 USA

Subject Category: ENGINEERING, CIVIL; ENGINEERING, ENVIRONMENTAL;

ENVIRONMENTAL SCIENCES

Title: Groundwater deterioration caused by induced recharge: Field survey and

verification of the deterioration mechanism by stochastic numerical simulation

Author(s): Yoneda M , Morisawa S , Takine N , Fukuhara S , Takeuchi H , Hirano T ,

Takahashi H , Inoue Y

Source: WATER AIR AND SOIL POLLUTION 127 (1-4): 125-156 APR 2001




Abstract: Our field survey showed that the quality of shallow groundwater around the

Katsura River in the Kyoto Basin was strongly affected by the infiltration of river water.

Furthermore, that the deterioration of the groundwater in the southern area to the west of the Katsura River may be related to the increase in groundwater extraction. To clarify the mechanism of groundwater deterioration, we have developed a stochastic method to simulate groundwater flow. The results showed that there was a large reduction in the groundwater level where groundwater extraction was intense and recharge flowed from the Katsura River to the high extraction areas in the southern region. Another simulation showed that if the groundwater extraction was 10% of the present removal rate, there would be little recharge from the Katsura River into the groundwater and the quality of the groundwater would be improved. Thus, we conclude that the cause of groundwater deterioration is probably due to the induced recharge of deteriorated river water from the

Katsura River.

Author Keywords: deterioration; groundwater; induced recharge; mechanism; numerical simulation; river water; stochastic simulation

KeyWords Plus: CONDITIONAL PROBABILITIES; ALLUVIAL AQUIFER; RIVER;

INFILTRATION; FLOW; RN-222; STREAM; WATER

Addresses: Yoneda M (reprint author), Kyoto Univ, Dept Global Environm Engn, Kyoto,

Japan

Kyoto Univ, Dept Global Environm Engn, Kyoto, Japan

Fukui Univ Technol, Dept Construct, Fukui, Japan

Publisher: KLUWER ACADEMIC PUBL, SPUIBOULEVARD 50, PO BOX 17, 3300 AA

DORDRECHT, NETHERLANDS

Subject Category: ENVIRONMENTAL SCIENCES; METEOROLOGY & ATMOSPHERIC

SCIENCES; WATER RESOURCES

IDS Number: 409AP

ISSN: 0049-6979

Title: Mobile organic sorbent affected contaminant transport in soil: Numerical

case studies for enhanced and reduced mobility

Author(s): Totsche KU , Kogel-Knabner I

Source: VADOSE ZONE JOURNAL 3 (2): 352-367 MAY 2004




Abstract: Mobile organic sorbents (MOS) such as dissolved and colloidal phase organic matter control flow of water and transport of solutes in soils. We studied the effect of

MOS on contaminant fate by systematic numerical case studies. The scenarios considered were (i) enhanced mobility, (ii) reduced mobility due to cosorption, and (iii) reduced due to cumulative sorption. The enhanced mobility and cosorption scenario require contaminant sorption to the MOS. The cosorption and cumulative sorption scenario require sorption of MOS to the immobile sorbent. Simulations were run for physicochemically different fractions of dissolved organic matter and two-model contaminants. Mobile organic sorbents mobility is characterized by a wide range of retardation parameters. Continued import of MOS to subsoil material high in MOS-specific sorption sites will increase the solid phase organic matter content. Enhanced mobility was observed for soils without MOS-specific sorption sites or for situations where MOS are in sorptive equilibrium with the immobile sorbent. Cosorption resulted in reduced contaminant mobility. The extent to which reduced mobility was observed depended on the ratio of the affinities of the free contaminant and the MOS-bound contaminant. As the sorption of the MOS-bound contaminants is controlled by the properties of the MOS, the characterization of these properties is a crucial step for the estimation of the effect of

MOS on contaminant mobility. Cumulative sorption resulted in reduced contaminant mobility as well. However, this result is the consequence of the increase of the sorption capacity due to the sorption of MOS, a long-term process that may last for years to decades.

KeyWords Plus: POLYCYCLIC AROMATIC-HYDROCARBONS; REACTIVE SOLUTE

TRANSPORT; UNSATURATED POROUS-MEDIA; FACILITATED TRANSPORT; IMMOBILE

SORBENTS; MATTER SORPTION; COLLOIDS; CARBON; FRACTIONS; COLUMNS

Addresses: Totsche KU (reprint author), Tech Univ Munich, Lehrstuhl Bodenkunde, Dept

Okol, Wissensch Zentrum Weihenstephan, Freising Weihenstephan, D-85350 Germany

Tech Univ Munich, Lehrstuhl Bodenkunde, Dept Okol, Wissensch Zentrum Weihenstephan,

Freising Weihenstephan, D-85350 Germany

E-mail Addresses: totsche@wzw.tum.de

Publisher: SOIL SCI SOC AMER, 677 SOUTH SEGOE ROAD, MADISON, WI 53711 USA

Subject Category: AGRICULTURE, SOIL SCIENCE; ENVIRONMENTAL SCIENCES; WATER

RESOURCES

IDS Number: 904BA

Title: Measuring the pollutant transport capacity of dissolved organic matter in

complex matrixes

Author(s): Persson L , Alsberg T , Odham G , Ledin A

Source: INTERNATIONAL JOURNAL OF ENVIRONMENTAL ANALYTICAL CHEMISTRY 83

(12): 971-986 DEC 2003




Abstract: Dissolved organic matter (DOM) facilitated transport in contaminated groundwater was investigated through the measurement of the binding capacity of landfill leachate DOM (Vejen, Denmark) towards two model pollutants (pyrene and phenanthrene). Three different methods for measuring binding capacity were used and evaluated, head-space solid-phase micro-extraction (HS-SPME), enhanced solubility (ES) and fluorescence quenching (FQ). It was concluded that for samples with complex matrixes it was possible to measure the net effect of the DOM binding capacity and the salting out effect of the matrix. It was further concluded that DOM facilitated transport should be taken into account for non-ionic PAHs with lg K OW above 5, at DOM concentrations above 250 mg C/L. The total DOM concentration was found to be more important for the potential of facilitated transport than differences in the DOM binding capacity.

Author Keywords: leachate; groundwater; dissolved organic matter; solid-phase micro extraction; fluorescence quenching; enhanced solubility

KeyWords Plus: POLYCYCLIC AROMATIC-HYDROCARBONS; SOLID-PHASE

MICROEXTRACTION; AQUATIC HUMIC SUBSTANCES; LEACHATE PLUME VEJEN;

LANDFILL-LEACHATE; SOLUBILITY ENHANCEMENT; FACILITATED TRANSPORT;

MOLECULAR-WEIGHT; PYRENE SORPTION; MODEL POLYMERS

Addresses: Persson L (reprint author), Stockholm Univ, Inst Appl Environm Res,

Stockholm, S-10691 Sweden

Stockholm Univ, Inst Appl Environm Res, Stockholm, S-10691 Sweden

Tech Univ Denmark, Environm & Resources DTU, Lyngby, Denmark

E-mail Addresses: linn.persson@itm.su.se

Publisher: TAYLOR & FRANCIS LTD, 4 PARK SQUARE, MILTON PARK, ABINGDON OX14

4RN, OXON, ENGLAND

Subject Category: CHEMISTRY, ANALYTICAL; ENVIRONMENTAL SCIENCES

IDS Number: 762QU

Title: The simultaneous modelling of metal ion and humic substance transport in

column experiments

Author(s): Bryan ND , Barlow J , Warwick P , Stephens S , Higgo JJW , Griffin D

Source: JOURNAL OF ENVIRONMENTAL MONITORING 7 (3): 196-202 2005




Abstract: Pulsed column experiments using Co, fulvic acid and porous sediment packing, along with up/down-flooding experiments using Eu, humic acid and intact sandstone blocks have been performed. The elution of metal and humic and their distribution along the sandstone columns have been measured. A mixed equilibrium and kinetic coupled chemical transport model has been used to simulate the results. In both cases, one exchangeable and one non-exchangeable component have been used to simulate the interaction of metal and humic substance. For the pulsed experiments, a simple equilibrium approach was used to model humic sorption, while a two component, kinetic model was required for the sandstone columns.

KeyWords Plus: NATURAL ORGANIC-MATTER; IRON-OXIDE; COMPETITIVE

ADSORPTION; SANDY AQUIFER; DESORPTION; SORPTION; ACIDS; DISPLACEMENT;

PARTICLES; MOBILITY

Addresses: Bryan ND (reprint author), Univ Manchester, Dept Chem, Ctr Radiat Res,

Oxford Rd, Manchester, Lancs M13 9PL England

Univ Manchester, Dept Chem, Ctr Radiat Res, Manchester, Lancs M13 9PL England

Univ Loughborough, Dept Chem, Loughborough, Leics England

British Geol Survey, Keyworth, Notts NG12 5GG England

RMC Ltd, Abingdon, Oxon England

Publisher: ROYAL SOC CHEMISTRY, THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON

RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND

Subject Category: ENVIRONMENTAL SCIENCES

Title: Modeling RBF efficacy for migrating chemical shock loads

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